Secure and Fast Near-Field Acoustic Communication Using Acoustic and Vibrational Signals

Saki NISHIHARA  Tadashi EBIHARA  Koichi MIZUTANI  Naoto WAKATSUKI  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E101-A   No.11   pp.1841-1848
Publication Date: 2018/11/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E101.A.1841
Type of Manuscript: Special Section PAPER (Special Section on Smart Multimedia & Communication Systems)
Category: Communication Theory and Signals, Digital Signal Processing
Keyword: 
near-field communication,  acoustic device,  communication system security,  

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Summary: 
In this paper, we propose a secure near-field communication (NFC) for smartphones by combining acoustic and vibrational communication. In our hybrid system, a transmitter transmits an encrypted message and encryption key from a loudspeaker and vibration motor, respectively. While the sound emitted from the loudspeaker propagates through the air, the vibration emitted by the vibration motor propagates through the body of smartphones. Hence, only receivers touching the transmitter can receive both the encrypted message and the key, resulting in secure communication. We designed a software modulator and demodulator suitable for the vibrational communication by using return-to-zero (RZ) code. Then we established a hybrid communication system by combining acoustic and vibrational communication modems, and evaluated its performance in experiments. The results indicate that our hybrid system achieved a secure (among physically contacted devices) and fast (800kbps) NFC for smartphones.